How to Thin Out Bulbs
Wherever you have planted bulbs in your garden, after a few years you may find that they stop producing flowers as freely as they did. This is usually due to overcrowding, which you won't be able to see, unless it's a bulb that is planted close to the surface of the soil (Nerine). Most bulbs are lifted and thinned or transplanted when they are dormant, but some resent drying out and prefer to be lifted when they are still in leaf - or in the green. These types include: Wood Anemone (Anemone Nemerosa), Hardy Cyclamen, Winter Aconite (Eranthis), Snowdrop (Galanthus Nivalis), Bluebell (Hyacinthoides), Snowflake (Leucojum).
Lifting and thinning bulbs means you can increase colonies and improve flowering next year. These other Workshops might also be helpful: How to store bulbs; How to plant a bulb in earth; How to plant a bulb in grass.

A fork; a spade; wheelbarrow or bucket; surface to work at.
Optional: thin gardening gloves; bonemeal; labels to mark which type of bulbs you have planted where.

Lift bulbs from the group above just after they finish flowering. For all other bulbs, lift when their leaves start to yellow. Use a garden fork to lift the clumps, taking care not to damage the outer bulbs.

At a work bench or table, work on each clump, dividing them by hand, first into smaller clumps, then into individual bulbs.

Remove dead or diseased material from around the bulbs, and discard any which look unhealthy. Clean the good bulbs ready for replanting, removing loose skins. Put each to one side - aim to replant as soon as possible. If there will be a delay, place the bulbs on a wire rack overnight. See Workshop: How to store bulbs.

Replant the bulbs as they were originally, in soil or in grass. Either plant them singly, or in small groups of 5 - 7 bulbs in one hole that is wide enough for them to spread their roots - leave a bulbs space between each. Plant bulbs at the same depth that they were before being lifted. Put a small amount of bonemeal into planting holes. Firm the soil around them and water in.